Bronx Councilman Fernando Cabrera is mounting a primary challenge against State Senator Gustavo Rivera–and says he’s open to joining the breakaway faction of Democrats that leads the body with Republicans if he wins.

Mr. Cabrera, a socially conservative councilman and pastor, has for months been mulling a run against Mr. Rivera, a popular lawmaker who replaced disgraced ex-State Senator Pedro Espada in 2010. Now, he says he’s officially in the running, with a campaign operation in place.

“The community asked for it,” Mr. Cabrera told the Observer. “They kept asking me to come forward and ask for the senate.”

Mr. Cabrera, who also serves as senior pastor of New Life Outreach International, accused Mr. Rivera of failing to secure enough resources for the district, which includes some of the city’s poorest neighborhoods.

“He has allowed politics to get in front of the community,” charged Mr. Cabrera. “He hasn’t brought a dollar. We haven’t had parks. We haven’t had schools.”

“At the end of the day, people are looking for visible, comprehensive changes,” he added, pointing to his own work on the council.

“I’m the only elected official in the whole district who’s bringing in resources,” he claimed.

According to labor sources, Mr. Cabrera was urged to run at the behest of State Senator Jeff Klein, the leader of the Independent Democratic Conference and a fellow Bronx elected, after Mr. Rivera hinted that he would throw his support behind Mr. Klein’s own challenger, Oliver Koppell. Like many in the Democratic establishment, Mr. Koppell has railed against Mr. Klein for abandoning mainline Democrats, claiming the power-sharing agreement has empowered Republicans and stymied progressive legislation.

“That’s funny,” he said, noting that giving up his council seat would mean a cut in pay. “Every time I’ve decided to run it’s because I have strong convictions to do it,” he said.

But when pressed, Mr. Cabrera admitted that he had, indeed, talked to Mr. Klein about running. “I will talk to everybody who’s willing to talk,” he said.

Mr. Klein’s office did not immediately respond to a request for comment.

Mr. Cabrera has spent recent weeks trying to line up support for his bid–and has suggested to some that he’s open to joining the IDC if it means added power, sources said.

In the interview, Mr. Cabrera would not rule out caucusing with the group and said he would do whatever it takes to ensure he achieves maximum power.

“I am going to work with those who are going to enable me to bring the power to my district … That’s what matters to the people in my district,” he said, explaining that his “guiding light” will be to do “whatever will take care of my community.”

“Whatever pans out I will follow that light,” he said. Still, he cautioned, “We’re dealing with a big hypothetical because it’s an eternity between now and then.”

Mr. Cabrera will begin collecting petitions next week, according to his campaign manager, Domingo Flores.

But the councilman–who faced ethical charges related to the Kingsbridge Armory–has an uphill battle. Mr. Rivera is popular in his district, and is expected to secure most establishment support.

“I can be very resolute in telling you that most of labor spent a whole lot of time and effort in getting Gustavo elected. I can’t imagine that anyone would back Cabrera,” said one labor source. “It’s a joke.”

As Crain’s New York Business noted earlier this year, Mr. Rivera has repeatedly broken from many of his Bronx colleagues, backing State Senator Daniel Squadron for public advocate over Tish James, who won her race, and endorsing former Council Speaker Christine Quinn for mayor over the county’s pick, Bill Thompson.

In a statement, Mr. Rivera said he was honored to serve the district and touted his “Democratic values.”

“The families of this community suffered through two decades of corruption in this seat, so I have worked since my election to bring integrity and honest leadership back to our district,” he said, running through his list of accomplishments, including helping to secure millions of dollars in pre-k funding, and securing $6 million to redevelop a local correctional center.

“We have done much, but I know we can do more if we stand together as Democrats for our Democratic values,” he added. “During the upcoming months, I look forward to having the opportunity to talk with my constituents about our accomplishments and how we can build a better future for our district and New York State.”